1. Field of the Invention
The present invention relates to a test system using a network. The present invention also relates to a motion control method for a driving simulator and a vehicle test system.
2. Description of Related Art
With recent advancement of communication networks such as the Internet and intranets, techniques capable of coupling various robots to each other or coupling a robot to an interface via a network have attracted attention (for example, see Japanese Patent Application Publication No. 2006-000977 (JP 2006-000977 A)). An integration test may be carried out with mechanical elements (such as an engine, a transmission, and a steering system, which are hereinafter referred to as “actual machines”) of a vehicle disposed in different locations using such communication control techniques. In this case, the test is carried out in a state where a simulated machine capable of simulating an operation of one actual machine is connected to the other actual machine, a simulated machine capable of simulating an operation of the other actual machine is connected to the one actual machine, and the actual machines and the simulated machines are connected to each other via a network to exchange data therebetween and to share the data.
In the test, each simulated machine has to operate in real time on the basis of data acquired from an actual machine operating in another location. FIG. 1 is a diagram schematically illustrating a test system according to related art in which an actual machine A1 and a simulated machine B1 are installed in a place (location 1), a simulated machine B2 and an actual machine A2 are installed in another place (location 2), the simulated machine B1 and the actual machine A1 are mechanically coupled to each other, and the actual machine A2 and the simulated machine B2 are mechanically coupled to each other.
The simulated machine B1 simulates the operation of the actual machine A2 and the simulated machine B2 simulates the operation of the actual machine A1. Accordingly, the simulated machine B1 and the actual machine A2 are connected to each other via a network and the simulated machine B2 and the actual machine A1 are connected to each other via the network.
However, when a simulated machine operates on the basis of data acquired via a network and a communication cycle (which is determined depending on a transmission cycle of a packet) is long, the time corresponding to the communication cycle may be required until an actual machine transmits the next data after transmitting data, the simulated machine cannot update the data during the time, and thus the simulated machine may not correctly simulate the state of the actual machine. Particularly, when a data value to be transmitted by communications rapidly varies, reproduction of the state may not follow the variation well and the test operation may be unstable. In this way, a communication delay has an adverse influence on the entire test system using a network.
A driving simulator includes input devices necessary for driving, such as a steering wheel, an accelerator pedal, a brake pedal, and a shift lever; actuators providing motions such as roll, pitch, and yaw to a driver seat; a monitor that displays a landscape appearing via a vehicle window; and a speaker that reproduces running sounds or collision sounds. The driving simulator can create various driving environments under controlled conditions and can reproduce vehicle behavior (hereinafter, also referred to as a “motion”) in the driving simulator such as rolling, pitching, yawing, and steering reaction force at the time of acceleration and deceleration, cornering, and braking. Accordingly, the driving simulator has been used for development of a vehicle system, study on interaction among a driver, a vehicle, a road, and traffic, and the like.
In addition to the driving simulator, equipment provided with a pair of front and rear bases movable to the front, rear, right, and left sides may be disposed as a vehicle test apparatus. A vehicle may be installed in the vehicle test apparatus and the vehicle may be tested, or a test piece-mounting vehicle frame may be installed in the vehicle test apparatus, mechanical elements or mechanical components (hereinafter, referred to as “test pieces”) such as a suspension system, a steering system, and a braking system of a vehicle may be installed thereon, and the test pieces may be tested (see Published Japanese Translation of PCT Application No. 2009-536736 (JP-A-2009-536736)).
When test pieces are installed in the vehicle test apparatus, virtual component parts which are installed in a computer and which are included in a model (hereinafter, referred to as a “vehicle model”) simulated by software are used as vehicle components other than the test pieces. A test piece is installed in a test piece-mounting vehicle frame, data obtained by measuring a motion of the test piece is input into a vehicle model, and a posture parameter, a steering reaction force, and the like acquired from the vehicle model are output.
The driving simulator and the vehicle test apparatus may be connected to each other via a communication line and may exchange data with each other in real time. In this case, when input data on a steering wheel, an accelerator pedal, a brake pedal, a shift lever, and the like necessary for driving is transmitted from the driving simulator to the vehicle test apparatus, the vehicle test apparatus applies the input data to the test pieces and the vehicle model and outputs a posture parameter, a steering reaction force, and the like acquired from the test pieces and the vehicle model. The driving simulator reproduces the posture parameter, the steering reaction force, and the like output from the vehicle model.
However, when the driving simulator and the vehicle test apparatus are simultaneously operated on the basis of the data acquired via the communication line and a communication cycle (which is determined by a process time of each terminal, a transmission cycle for a packet, and the like) is long, a delay corresponding to the communication cycle occurs until the driving simulator transmits operation data, the vehicle test apparatus calculates and transmits output data corresponding to the operation data, and the driving simulator receives the output data and feeds back the output data to a driver. Accordingly, the driving simulator cannot update data during the delay and thus the driving simulator may not correctly determine performance of the test piece. Particularly, when the value of the transmitted data rapidly varies, reproduction of the state may not follow the variation appropriately and the test operation may be unstable, thereby causing resonance. Thus, when a communication delay of a predetermined time or more is present, it is difficult to perform real-time simulation and the entire vehicle test system is adversely affected.